The present invention relates to a vacuum brake force booster for use with automotive vehicles of the type comprising a vacuum housing sealingly subdivided, through an axially movable wall, into a vacuum chamber and a working chamber. A mechanically actuable control valve is provided for connecting the working chamber to the vacuum chamber and to the atmosphere, respectively, and the axially movable control valve housing is made of a thermoplastic material accommodating, within an axial bore, a rubber-elastic reaction disc in abutment with a pressure plate of a pushrod for transmitting the brake force to an actuating piston of a master cylinder which is located on the vacuum side at the vacuum housing. The movable wall is in communication with the control valve housing and a guiding sleeve is provided to axially guide the pushrod. The guiding sleeve is provided with a radial flange.
A vacuum brake force booster of this type is taught by Applicant's prior application P 37 09 172. That brake force booster provides for the radial flange of the guiding sleeve to be axially supported within the bore of the control valve housing and is straddled, in axially form-locking manner, by a holding member in communication with the control valve housing.
One disadvantage of this brake force booster is the heavy load on the control valve housing in the area of the support of the radial flange of the guide sleeve upon occurrence of lateral forces acting upon the pushrod increasing the risk of damage to the control valve housing which is a thin wall in that area.